


Fish Out of Water

by TheCreativeCasseroles



Category: Batman - All Media Types, Batman Beyond, DC Animated Universe (Timmverse)
Genre: Alternate Universe - Merpeople, Jason just wants his legs back, Magical girl Terry, Mama Mary is scared and confused, he turns into a mer, she just wants her kids
Language: English
Status: Completed
Published: 2020-07-27
Updated: 2020-08-06
Packaged: 2021-03-06 02:35:01
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,364
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25555945
Author URL: https://archiveofourown.org/users/TheCreativeCasseroles/pseuds/TheCreativeCasseroles
Summary: Gotham Harbor was protected by mer known as the Bat. Twenty years ago or so the Bat disappeared. Then, a new Bat mer appeared.This, may or may not be connected to Mary McGinnis’s missing sons.Especially when the Bat was forced into an aquarium. And mysteriously got out.
Comments: 22
Kudos: 70





	1. Chapter 1

**Author's Note:**

  * For [owlady](https://archiveofourown.org/users/owlady/gifts).



Mary was running around in the rain. Searching for her youngest. She couldn’t lose him too. They still haven’t found-

Stopping short, Mary found herself at the harbor… where the new Bat Mer was cradling Matt on the beach.

She nearly stumbled as she started back up again. Faster this time. But when she did get to them she fell to her knees.

Those white eyes landed on her with a laser focus.

“M-Matt.” It-he rasped, voice low and cracking. As if he hadn’t spoken in ages.

It took a moment for her to realize that he had spoken her son’s name. She nodded with a jerk. “Y-yes. Matt. My son.”

Mary reached out to take him when the mer flinched backwards. As… as if he were _afraid_ of her.

Something lodged itself into her throat at the thought. “Please.” Her voice broke. Tears began to mix with the rain. Her hair stuck to her face and neck. “Please give me back my son.”

They stared at one another for what felt like an eternity. And then…

“Mo…m…? Mom?” The Bat asked. And that time the voice sounded like one she hadn’t heard for two months.

“Terry?” She gasped.

His eyes widened. He suddenly tensed, and without any warning he stole Mary and Matt into the water.

.

.

.

She remembered when her son started acting strange. It was some time after Warren’s death when he applied for a job at the nearby ocean rehabilitation center. Tim Drake was a good man that reassured that Terry would be shadowing for quite some time before he got any hands on experience to make sure he wouldn’t get hurt. That and he would get the appropriate hours since he was still a minor. And yet…

And yet he still went out for long periods of time. Mostly at the harbor. At least that’s what Terry told her. Helping clean it up. It was nice, and very kind, but Mary would just like it if her son was _home_ more often.

Even she could tell that this was affecting Matt.

Maybe all of this was because of Warren’s death. Terry wanted to do good in the world, by helping animals, and cleaning up the local areas. The ocean _was_ where life started after all.

It’s where the mers lived.

It’s where the new Bat Mer showed up.

Mary wasn’t quite sure how to feel about the new Bat Mer. It had been at least twenty years when the last Bat Mer sighting was… and it was clear that these two mers were not the same mer. Perhaps the new one was related to the last one. Perhaps it was just happenstance. But it was there and mers can be dangerous. Now she knew that mers were much like people, but they were… stronger. Bigger. Once she saw how big a whale mer could get.

And if Terry might meet up with just the wrong mer while at the harbor…

Mary didn’t dare to entertain that thought.

But then a couple of years went by, and Terry was soon to graduate. He was doing great at the rehabilitation center, his grades could be better, but he was also getting more time with her and Matt. Not to mention that girlfriend of his.

Dana Tan was a keeper, this she knew.

But then the new aquarium opened. And her son disappeared. And the Bat Mer found its way into the aquarium.

There was no correlation between these events. Mary lied to herself when she said that out loud one night as she stared at a photo of her family, back when her kids were small children. Back when Warren was alive. Before the divorce.

It was pretty much illegal for any mers to be in an aquarium. And yet that aquarium had the Bat Mer. And her son was gone. Mary had a feeling that maybe… maybe Terry was involved. She could practically see it in her head. A fight down at the dock. The henchmen of a greedy corporate bastard trying to wrangle the Bat into being the grand attraction. Terry seeing this and fighting to free the Bat. Terry getting overwhelmed. Terry loosing and-

Mary did not want to entertain all those dark thoughts in her mind.

She did know that the people at the rehabilitation center were doing their damned best to shut the aquarium down for having a mer. Commissioner Barbara Gordon was doing her damned best to investigate.

But Mary knew that as much as Gordon wanted to purge the police force of all the corrupt, that there would always be at least one that was stealthy enough to stay. And there was just enough corruption still rooted within that withheld her investigation of the aquarium.

Then Matt wanted to _go_ to that damned aquarium. To see the Bat.

The Bat saved her son before. She thought that Matt wanted to see if it was really the Bat.

And when they got there, it really was the Bat.

It was covered head to tail with black scales with flecks of red. Its fin was red and it looked like it had additional fins on its arms. The gills on its neck were lined with red, and frighteningly, its eyes were pure white. No hair. Two long spines that looked like bat ears rose from the top of its head.

Some mers top half looked more human than others. With this, mer, it was clear that this was more animal than man.

It looked… sad. Hurt. And it stared at Matt.

She had to suppress a shiver when she noticed that tidbit. They quickly went through the aquarium and left not long after that. But then Matt wanted to go back.

Again.

Again.

And again.

It was after the fifth time that Mary put her foot down. The aquarium was certainly taking quite a bit of money out of her pocket, and with Terry still missing, Mary was under quite a bit of stress. It was understandable really. She couldn’t exactly say her reasons to Matt though. He was only a child. He shouldn’t bear her burdens.

So two months had passed since her son disappeared and the Bat Mer was stuck in the new aquarium. Mr. Drake had promised her that they were still searching for Terry, and Commissioner Gordon had promised the city that they would get the Bat back into the harbor.

And crime had risen like the incoming tide during that time. Then one night, Matt snuck out. And Mary felt her world crumbling under her feet.

She called the police. She went out into the oncoming storm.

Mary felt a pull to the harbor. She ran.

.

.

.

Groaning, Mary found herself waking up. For a moment she couldn’t remember what happened to her, and why she felt like she was on rocky ground. Mary didn’t even realize there was something chattering in the background until everything went silent.

And then Mary McGinnis remembered.

Gasping, Mary’s eyes shot open as she popped up from her lying position, hand reaching out for a child’s. Quick larger hands went to hers. Human hands made out of skin and not scales.

“Breathe Mary, breathe.” Another familiar worm its way through Mary’s panic.

Startled, Mary recognized who it was.

Tim Drake.

But…?

“You’re okay.” He said with a calm and soothing voice.

“Matt.” She croaked. “He-he was hurt. A-and he was at the harbor.”

The woman tried to scramble to her feet.

Tim held on to her as her legs gave away.

“It’s okay. He’s fine.”

“How do you know?” Mary snapped at him. “He-I-we-“ she cut herself off. Her face paled. Was what she remembered correct? Or was it just her grief stricken mind playing tricks on her?

Did the Bat really sound like Terry? And was she and her son spirited away by the mer?

“Personally I thought it would be best to bring him to a bed, and you too, but _nooooo_ the Bat Brat decided to go fucking _feral_.” A new voice cut through.

Looking around, Mary searched for the voice. Doing so brought some… very important details that she missed into light.

She was in a cave.

A modified cave with all sorts of signs of human activity dwelling within.

That had a giant pool of water to her right.

With multiple people within…

Human…

_And mer._

The only human she recognized, besides Tim Drake, was his wife Stephanie.

Mers of various sizes were in the water. One of which was the largest whale mer Mary ever saw.

And then there was the Bat Mer.

The Bat Mer was half out of the water, holding her son close to his chest, staring right at her. One hand reaching out to hold on a small portion of her coat. Immediately it made Mary think of a child.

“Although I would probably go absolutely bat shit like him if I was in his situation. Probably would do worse than him if I’m honest.”

Mary snapped back up to see a more… human looking mer gave her a sharp smile. One that looked like he could be only a few years or so older than Mary. The white streak in his black hair flopped down near his impossibly teal eyes. He still had black and red scales and all the small things that indicated his ‘merness’ however.

“Actually I did do worse.” His teeth looked like that of a predator’s.

Mary could not stop the shiver that went down her spine.

The black and blue mer slapped the one who talked upside at the back of his head. This one looked more mer than the first. But somehow younger. He had the same black hair as the first. His eyes were blue and his skin had more of a tan to it. Well, the skin that wasn’t covered with scales.

“Sorry about my little brother,” the black and blue scaled mer said, smiled wide and meant to disarm despite the sharp teeth, “he’s just full of bitter bean juice.”

She felt more than heard Tim huff. “You should stop being mean to coffee. It’s not that bad.”

The black and blue mer scoffed. “Yeah no. It is not.”

“I have to agree with Drake on this one.” The smaller whale mer, who was wearing the top portion of the Gotham Rehab wetsuit?, spoke up.

His eyes were a green that felt unreal, and his skin darker than the second mer. Unlike the other two mers he was part orca and not fish. (Although Mary couldn’t identify what types of fish they were part of, orcas were a bit more… recognizable.) He was younger than the first two, perhaps looking to be in his late 20’s if that was possible. His hair was black just like the others and Mary’s heart leapt up once she realized… he looked an awful lot like her sons.

If her sons were part mer, of course.

“But it’s gross!” The second mer squawked. “It’s disgusting and bitter!”

“Well if someone actually put sugar in it then maybe they would like it.” Tim… snarked? He was snarking at the mers?

“But that doesn’t mask the bitterness! I can still taste the bitter beans, I’m telling you!”

“That’s ‘cause you’re just a pussy.” Stephanie pipped up.

“See, Steph, it’s times like this you're my favorite.”

The third mer scoffed. “Who would want to be _your_ favorite, Todd?”

“Kids.” The largest mer in the cave spoke. His voice soft, but low, took the attention of everyone in the cave.

He was more than likely related to the smaller whale mer, as he was also part orca, and looked… frighteningly familiar. His hair was gray, his eyes an icy blue, and wrinkles were interrupted by scars… and in the middle of his chest, was a mark in the shape of a bat.

A chorus of ‘sorry dad’ echoed in the cave.

What.

“What.” Mary deadpanned aloud. It sounded monotone even to her.

She turned her attention back to Tim who had the decency to rub the back of his head rather sheepishly.

“So Bruce here, the big Orca Mer?” Tim gestured to the mer. Mary nodded. “He adopted all of us. We’re part of his pod.”

“I’m pretty sure I’m not technically his kid since we’re married, Tim.” Stephanie spoke.

“Daughter-in-Law then.” Tim said.

“Part of my pod.” The whale mer, _Bruce,_ grumbled.

The woman’s mind whirled around at the newfound information. “B-But that’s not legal? Mers can’t adopt humans?” She stammered.

The second mer shrugged. “That hasn’t exactly stopped Bruce. It’s quite the problem at this point. Like, nearly every so often he takes a kid, human or mer, and basically goes ‘mine.’”

“I do not do that.” Bruce grumbled once more.

The first mer somehow snorted and scoffed at the same time. “You basically kidnapped me when I fell off of that boat. Now the new Bat Brat is following in your footsteps.” He gestured over to Mary and Matt, who was still in the Bat Mer’s hold.

Everything went chaotic for a brief moment.

“Enough!” Bruce shouted, his voice booming into Mary’s bones.

She heard a whimper.

Looking down, she saw that the Bat Mer’s clutch on her son and her coat got tighter. And her son’s eyes were wide open.

“So are we in like,” her youngest spoke, voice soft, “The Bat Cave or something?”

The Bat Mer calmed down, and chuckled. “Or something.” He rasped.

“He speaks!” The first mer threw his hands into the air. She saw a reddish pink webbing between each finger.

The Bat Mer grumbled.

Moving from Mary’s side, Tim got closer to the Bat. “They’re awake now.” He spoke quietly. “You can let go now.”

That was the wrong thing to say as the mer snapped his head to the man, face twisted into anger, teeth bared. He even snarled.

Tim was quick to put his hands up. Hands open and palms out. Not a threat. “We’re not going to take them away from you.”

Slowly, the second mer swam closer. “We just want to help you.” He said.

“Dick…” Tim said warningly.

That… surely wasn’t the mer’s name was it? The tone didn’t indicate an insult…

“Don’t worry Timmy, I got it.” The mer winked at Tim. “Now don’t freak out at what I’m going to do…”

She could hear Tim mutter the words, “that always makes them freak out,” when the second mer made his move.

Lightning quick, he reached into the Bat’s gills and _yanked_ something out. With a disgusting squelch, a… necklace of all things popped out.

And then the reaction was immediate. With a shaky breath, scales and fins bleed and receded, turning into black hair and pale white skin. Tail split into legs and pale blue eyes faded into view.

“Holy shit.” Terry shuddered out as the transformation completed.

Mary’s mind screeched. It stopped. It crashed.

It. That. What?

Her. Terry. The Bat Mer.

The Bat Mer turned into her son.

_Her son was the new Bat Mer._

“I’m never staying as a mer for two months again.” Terry said as he stared at the black and blue mer.

Then the first mer shouted, “HOW THE FUCK DO YOU THINK I FEEL? I’VE TURNED INTO A MER FOR FUCKING YEARS.”

Mary fainted.


	2. Chapter 2

**Notes for the Chapter:**

> So. Owlady gifted me with a fanfic. It’s not long, but I’m retaliating with a new chapter. Hope ya like it Owl!!

Holding a tight grip on her warm cup of tea, Mary watched keenly as Stephanie helped Terry learn how to walk again.

It… was _wonderful_ to see her baby boy again. He was alive. He was with her. But he was also the new Bat. He somehow turned into a mer, got stuck in that form for _months_ , and had to _relearn how to walk._

 _’Things could be worse.’_ She thought to herself. _’He could’ve been stuck in that form forever. Stuck in the aquarium for the rest of his life. Dead.’_

Unfortunately she couldn’t stop those thoughts. She watched as her son, clothed with warmer swimwear so he could go back into the water any moment, walked on trembling legs. Stephanie held his hands with hers as Terry followed her like a newborn fawn.

Mary felt jealous. Mary felt sad. Mary felt horrified.

All this time. Her son was out in the ocean. Fighting. Protecting.

And there was Matt by the water. Playing with one of the mers. The one that took the necklace out of Terry’s… gills. They looked happy.

Both of her children looked happy.

“How?” She finally rasped. She winced at the roughness of her voice and took another drink of her tea. It was not only soothing to her throat, but to her nerves as well.

“See, for a long time we were trying to figure that out ourselves.” Tim said. He had been right by her side the whole time. Keeping an eye on her.

She wasn’t sure if she should feel bitter or thankful for that.

“What do you mean?” She asked as she turned to face him.

“Well,” he began, “Terry managed to get his way into the cave and stole a necklace. That same one that was stuck in his gills earlier. That necklace is special due to the magic embedded into it to help enhance a mer’s power.”

“And… Bruce, he used to use it when he was younger… right?”

Tim nodded. “He didn’t actually used it as long as other necklaces, but it did get the work done. But the thing is, it shouldn’t be able to make humans into mers. I’ve worn it before, Steph worn it before, and many others, but never has it turned them into mers.”

Mary didn’t know what to say.

“Jason was a bit jealous to say the least. He used to be human after all.” Tim said calmly.

Mary whipped her head over to him at that. “What? But you said-“

“I said the necklace doesn’t turn humans into mers. But Jason, well, long story short, in order to save his live, some people outside of the pod put him into a special pool that turned Jason into a mer. He’s still pissed about it.”

Staring wide eyed, Mary turned to the direction Tim was looking at. The red and black mer with the white streak in his hair.

“Your son’s an anomaly, Mary.” Tim stated. “And for a while he couldn’t quite actually comprehend a lot of things while a mer. It took a bit for us to help him. But he never stayed as a mer for longer than a day.”

Mary stayed quiet.

The black and blue mer did a trick. Water from the splash hit Matt who laughed. Terry nearly stumbled, but Stephanie held on. With a determined grin Terry continued to walk.

“Terry’s strong.” Mary finally said. Her voice was quiet. Not quite a whisper, but near close.

Out of the corner of her eye she saw the older man nod his head. “That he is.”

Slowly the water got darker as two mers came closer to the surface. Bruce and his son came up with… food.

“Bruce? Is that a sunfish?”

Bruce began to grumble something under his breath as his son spoke up. “Unfortunately father and I couldn’t find anything other than… this disgrace of the sea to capture. Mathew will name him.”

“Wait what?”

“Yes, this is your new pet. You must take care of him wisely. Although the Sunfish is quite… unique that you don’t really need to take care of him much. Really, a good pet to take care of.” The son said.

“Hold on, don’t I get a say in whether or not my son can have a-a pet _sunfish?”_ Mary spoke loudly.

“Yeah.” Terry piped up. “Besides, you never captured a pet for _me._ ”

The son gave Terry a flat look. “You wouldn’t accept the seal.”

Mary sighed heavily as she watched the chaos by the water. Matt was not going to keep the sunfish. Even if he decided to name it ‘SunBoy’.

Her life was so much simpler before. But, she supposed that, with time, maybe she could get used to this. After all, it felt like ages since she saw her children this happy.

**Author's Note:**

> Okay so, back in May, when the mermay was actually happening, Owl and I were talking about this super cool Mer idea of hers and I may have done a small dabble. An itty bitty dabble that made me go “oh wait no I wanna write more.” Except I may not have written any more until now. In July.
> 
> Whoopsies?
> 
> Anyway, this is for you Owl! Hope Y’all like it!
> 
> Also Cass and Duke are out in the ocean fighting ocean crime and Barbara is off bringing the aquarium down.
> 
> And yes. Matt freed Terry the Bat Mer Free Willy style. Then Terry yoinked his brother.
> 
> Edit: now with a proper name!


End file.
